|
12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061 |
- keybrd Tutorial 4 - Connecting split keyboards
- ===============================================
- Split keyboards have left and right parts:
- * one keyboard half contains the controller and USB port.
- * the other keyboard half can contain shift registers or an I/O expander.
-
- The two halves need to be connected.
- The preferred connection method depends on the number of keys, number of available controller pins, cable flexibility, LEDs, and cost.
-
- ## Split keyboard connections table
-
- | connection type | controller pins | wire count | max keys |
- |------------------------|:---------------:|:----------:|:--------:|
- | just cable | 3 | 6 | 9 |
- | just cable | 3 | 7 | 12 |
- | just cable | 4 | 8 | 16 |
- | just cable | 4 | 9 | 20 |
- | | | | |
- | 2 PISO shift registers | 3 | 5 | 16 |
- | 3 PISO shift registers | 3 | 5 | 24 |
- | | | | |
- | I/O expander SPI | 4 | 6 | 64 |
- | I/O expander I2C | 2 | 4 | 64 |
-
- Fewer wires makes a cable more flexible.
- A flexibility cable makes it easy to position the keyboard and route the cable.
- But if there are enough pins on the controller, using just a cable with more wires is simpler and costs less.
-
- I/O Expanders can power LEDs, while PISO shift registers can not.
-
- I2C is fast enough for scanning up to 5 rows.
- SPI is much faster, but requires 2 additional wires.
-
- More scanning options are reviewed at http://www.openmusiclabs.com/learning/digital/input-matrix-scanning/
-
- ## Cables table
-
- | connector name | wire count |
- |-------------------------------------------------------|:----------:|
- | TRRS | 4 |
- | 6-pin mini-DIN connector (PS/2) | 4 |
- | USB 2 | 4 |
- | 4P4C Modular connector (RJ9, RJ10, RJ22) handset plug | 4 |
- | 6P4C Modular connector (RJ-14) 2-line phone | 4 |
- | 6P6C Modular connector (RJ12) 3-line phone | 6 |
- | eSATA | 7 |
- | 8p8c Modular connector (RJ45) Ethernet | 8 |
- | USB 3.0, 3.1 | 9 |
-
- Only ready-made cables that are widely available are listed.
- There are hundreds of other connectors listed at http://pinouts.ru/
- There are also wireless options at the expense of adding complexity and maintaining a battery.
-
- The 8-wire "GearIT Cat 6 Ethernet Flat Patch Cable 7 Feet" is very flexible.
- It's available at Walmart (9/19/16) if you want to feel the merchandise before you buy.
- All the modular connector cables are available in the flat form factor.
-
- For prototyping on perfboards, consider a 0.1" header.
-
- <br>
- <a rel="license" href="https://creativecommons.org/licenses/by/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://licensebuttons.net/l/by/4.0/88x31.png" /></a><br /><span xmlns:dct="http://purl.org/dc/terms/" property="dct:title">keybrd tutorial</span> by <a xmlns:cc="https://creativecommons.org/ns" href="https://github.com/wolfv6/keybrd" property="cc:attributionName" rel="cc:attributionURL">Wolfram Volpi</a> is licensed under a <a rel="license" href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.<br />Permissions beyond the scope of this license may be available at <a xmlns:cc="https://creativecommons.org/ns" href="https://github.com/wolfv6/keybrd/issues/new" rel="cc:morePermissions">https://github.com/wolfv6/keybrd/issues/new</a>.
|